Evaluation of Payment Channels for Bitcoin Exchange Inflows and Outflows

Abstract: With increasing popularity, the scalability of blockchain-based crypto-currencies becomes an urgent concern. Bitcoin, among other crypto-currencies, have known limitations in transaction throughput and speedbut no agreed upon solution. Many of the proposals increasing throughput also increase the load on the Bitcoin network. Lightning is a proposal enabling payments to be conducted without affecting the Bitcoin network. Lightning is a protocol using payment channels to enable instant and cheap payments using the blockchain for security. With Lightning, payments can be sent through a network of nodes connected by payment channels. In this thesis, the current state of Lightning is explored and an evaluation for use on Bitcoin exchanges is performed. The usability, privacy and security of Lightning are the topics evaluated. In order to evaluate the usability, an exchange interface application was built allowing deposits and withdrawals using Lightning. The protocol specification and relevant literature are examined in order to evaluate the security and privacy of Lightning. The exchange interface showed that Lightning can be integrated into an exchange and provide a fast and cheap way to deposit and withdraw money for clients. In this paper some integration designs are proposed and ways to improve the client user experience are discussed. The Lightning node implementations need to mature a bit before real usage and there are some security issues that also need to be considered. With monitoring and network analysis the privacy can be compromised.